The compound N-[2-(diethylamino)ethyl]-5-[-(5-fluoro-1,2-dihydro-2-oxo-3H-indol-3-ylidine)methyl]-2,4-dimethyl-1H-pyrrole-3-carboxamid, also named sunitinib (Formula I) has been shown to act as an inhibitor of protein kinases.

WO 01/60814 generally relates to pyrrole substituted 2-indolinone protein kinase inhibitors. Examples of salts for the general class of compounds are generally referred to, such as positively charged moieties including quaternary ammonium, salts such as the hydrochloride, sulfate, carbonate, lactate, tartrate, malate, maleate, succinate; and negatively charged species. WO 01/60814 is silent as to the preparation of and the nature of specific crystal forms of salts.
In WO 03/016305 it is said that the free base and salts of sunitinib (e.g. cyclamic acid, maleic acid, hydrobromic acid, mandelic acid, tartaric acid, fumaric acid, ascorbic acid, phosphoric acid, hydrochloric acid, p-toluenesulfonic acid, citric acid, and malic acid salts) had been screened for properties related to the processing of the salt and the preparation of oral pharmaceutical compositions therefrom, including, for example, crystallinity, toxicity, hygroscopicity, stability, and morphology, but only malate salt was chosen from the screening and only two crystal forms of sunitinib L-malate were specifically disclosed.
Salts often improve physical and biological characteristics of mother compounds without modifying primary pharmacological activity, based on mechanism of action.
Thus there is a continuing need to obtain new salts of sunitinib having improved physical and/or chemical properties. The present invention satisfies this need by providing new salts of sunitinib with a markedly enhanced solubility in water or aqueous media as an essential property of active pharmaceutical ingredients determining the performance of pharmaceutical formulation.